Thickened lubricants



THICKENED LUBRICANTS Everett C. Hughes, Shaker Heights, and Ernest C. Milberger, Maple Heights, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ghio No Drawing. Application November 2, 1951 Serial No. 254,634

8 Claims. (Cl. 252-25) This invention relates to an aerogel grease of good high temperature stability and water resistance.

While the word grease has usually been employed to describe an oil thickened with a soap, it is here used in a broader sense to include any thickened lubricant.

It is generally known that soap-base greases break down at high temperatures, of the order of 300 to 400 F. This breakdown is accompanied by an irreversible change in the grease structure, so that upon cooling the grease is observed to have lost its greaselike characteristics. The aerogel greases usually are far superior to the soap base greases in stability at high temperatures as the following table shows:

However, after heating at high temperatures some aerogel greases tend to lose consistency upon stirring. This is undesirable because there are many field applications where a grease is agitated or worked while subject to a high temperature and it is important that the grease retain its consistency under these conditions and subsequent thereto.

Accordingly, it is an object of the present invention to provide an aerogel grease having improved stability at high temperatures, particularly after working at high temperatures.

In accordance with the invention, this object is accomplished by incorporating a water-miscible or watersoluble amine having at least two polar groups in an aerogel grease composition comprising a lubricating oil thickened with a non-abrasive, inorganic thickening or gelling agent, and particularly finely divided silica, a silica aerogel being illustrative. The thickened lubricant so prepared has excellent temperature susceptibility properties.

The grease is also rendered more or less resistant to deterioration by water by incorporating a hydrophobic cationic surface-active water stabilizer therein in the form of amine O," l-jS-hydroxyethyl 2-heptadecenyl imidazoline.

The presence of the amine in an amount to obtain improved high temperature stability does not markedly affect the consistency of the thickened lubricant, i. e., the

States Patent amount of the inorganic gelling agent to impart a given consistency to the thickened lubricant is not materially modified. Furthermore, the inclusion or the amine will not effect a change in the consistency of the thickened lubricant upon storage. The amine likewise does not aifect the water-resistance imparted to the grease by the hydrophobic cationic surface-active water stabilizing agent.

Due to the inorganic nature of the gelling agent, the thickened lubricant has excellent storage stability. This is to be contrasted with the heat susceptibility and deterioration of fatty materials in soap-base greases.

The preparation of the grease is simple and readily adaptable to continuous operation, as contrasted with the involved grease-making techniques which are often considered in the industry as an art.

The oil stock used in making the thickened lubricant may be widely varied, as contrasted with present greasemaking requirements in which the oil in many cases must meet certain critical specifications.

In addition, the avoidance of the use of soap permits the manufacturer to be independent of the fat supply, which is important in periods in which fats and soaps are scarce and, many times, of pronounced non-uniformity.

The inorganic gelling agent to be used in making the thickened lubricant in accordance with this invention may be any inorganic material which forms a gel with a lubri eating oil and which is so finely divided as to be nonabrasive. The preferred materials are the aerogels, which may be formed from any material not incompatible with oil, such as silica, alumina, and other gel-forming metal oxides.

A series of silica aerogels which can be used as the inorganic gelling agent of the invention are marketed under the trade name Santocel.

Santocel C is prepared from a sodium silicate solution in the following way: The solution is neutralized with sulfuric acid and then allowed to stand until the mixture sets to form a hydrogel. The by-product sodium sulfate is washed out by the repeated washings with water. The continuous water phase in this hydrogel is then replaced by continued washing with alcohol until an alcogel is formed. In order to remove the liquid phase without a collapse of the gel structure, the alcogel is placed in an autoclave which is then heated above the critical temperature of the alcohol and the pressure is allowed to increase to a point above the critical pressure of the alcohol. The vent valve is then opened and the alcohol allowed to escape. Under these conditions, the silica gel structure remains practically undisturbed and the liquid phase of the gel is replaced with air. The material is then reduced in particle size by blowing it through a series of pipes containing sharp bends with jets of com pressed air. Santocel C has a secondary agglomerate particle size of about 3 to 5 microns.

Santocel A is prepared as set forth for Santocel C up to the point of removal of the product from the autoclave. This material is run through a continuous heating chamher where it is heated for /2 hour to a temperature of about 1500 F. to eliminate the last traces of volatile material. It is then broken down in a reductionizer or miconizer to a particle size of about inch in diameter. The solids content of the original hydrogel used in preparing Santocel C is approximately 25% higher than that of Santocel A.

AR is a modification or" A, difiering only in that the material is reductionized to about the same particle size as C, approximately 1 to 6 microns in diameter.

-ARD is a modification of AR, differing only inthat- ARD is densified by extracting air under vacuum, and therefore has a smaller volume than AR.

AX is an A which has not been devolatilized.

CDV is a C which has been devolatilized as set forth for A. CDv is reductionized before being devolatilized.

CDvR difiers slightly from CDV in that the CDvR has been devolatilized just after heating in the autoclave and then reductionized. It differs from CDv in that the latter is reductionized before being devolatilized.

The primary differences between the As and the CS are as follows:

(1) The Cs are prepared from a sodium silicate solution containing 25% more silica than the As. Therefore, in general the As are lighter and composed of smaller particles than the Cs.

(2) The As have undergone a devolatilization step in their preparation.

The following are the bulk densities of preferred silica aerogels:

Density, grams per ml.

In general, AR and ARD show superior gelling ability and the As in general are better than the Cs. Silica aerogels which have been devolatilized generally have a higher gelling efiiciency than the undevolatilized aerogels.

Other types of inorganic gelling agents which may be used include a Fumed Silica marketed by B. F. Goodrich Company. It is finely divided and appears very much like an aerogel. It is made by a combustion or vaporization process, as a source of white carbon black for the rubber industry. The particles are several microns in size and porous in nature.

Another material is Linde Silica Flour. It is very similar in physical appearance to the silica aerogel. The particle size of the silica is purported to be 0.01 to 0.05 micron and to be manufactured by burning silicon tetrachloride and collecting the combustion product on cool plates analogous to the production of carbon black. The particles are thought to be aggregates or clusters of particles rather than of sponge-like character.

Still another inorganic gelling agent known is Ludox silica which is known as a silica sol, and silica derivatives thereof- It has a particle size of the order of 0.01 to 0.03 micron.

In preparing thickened lubricants it is necessary to remove the water from the sol and replace it with an oil. This is possible by formulating the lubricant and removing the water by flash distillation or azeotropic distillation.

No attempt is made to enumerate all of the inorganic gelling agents which will be suitable, nor to present examples of all of them since the novel aspects of the invention reside in water-proofing the lubricant rather than the use of novel gelling agents per se.

The lubricating oil to be used in the process may have any lubricating viscosity. It may be raw oil, acid-refined, or solvent-refined, as required for the particular lubricating need.

The nature of the base oil has been found to make little difierence in the relative consistencies of the thickened lubricants and conventionally (acid) refined oils produce slightly thicker lubricants than solvent refined oils. EX- cellent working stability is obtained regardless of the type of the base oil. An increase in the viscosity of the base oil, as might be expected, brings increased viscosity to the thickened lubricant and minimizes bleeding. The change is relatively small and fairly linear. The viscosity of the oil does not afiect the working stability of the lubricant.

The relative proportions of the inorganic gelling agent and the oil will vary somewhat depending upon the desired body in the thickened lubricant, the gelling ability of the inorganic gelling agent and the viscosity of the oil used.

It has beenwnoted, ..for instance, that with the Linde Silica Flour, the lubricants are somewhat harder, i. e., have a lower penetration than lubricants containing the same weight of Cantocel. Lubricants made with low viscosity oils require a somewhat larger amount of the inorganic gelling agent to give a lubricant of the same penetration. The thickened lubricant may vary in consistency from the consistency of a slightly thickened oil to a solid or semi-solid of grease-like consistency. In general, the amount of the inorganic gelling agent falls within the range of 5 to 20%, and in most cases would fall within the range of 7 to 12% The amount of the inorganic gelling agent, as might be expected, affects the consistency of thethickened lubricant in that an increase in its concentration brings a corresponding increase in consistency. The range is'fairly linear and the amount of the gelling agent can be selected with relation to the consistency desired in view of the information in the following examples. While the difieronce is slight, the lubricants made with lower concentrations of gelling agent possess better working stability, while lubricants with larger amounts of gelling agent show slightly improved temperature susceptibility characteristics. The bleeding tendencies are decreased by increasing concentrations of the gelling agent.

In general, the properties of the thickened lubricants are remarkably independent of the composition variables and are not critical. The relative concentration of the gelling agent effects the most significant alteration, particularly with regard to the final consistency of the product. This permits the manufacture of thickenedlubricants having a wide variety of consistencies.

A wide variety of water-miscible or water-soluble amines can be employed in accordance with the invention to improve the high temperature stability of aerogelbase greases. Amines which are water-immiscible, i. e., are oleaginous in character, cannot be used, because they are hydrophobic. The amine must be hydrophilic, for reasons which'will be apparent from the theory of the action of the amine, set forth later. Hydroxyl groups increase the hydrophilic character of the amine.v

The amine may have from three to ten carbon atoms and must contain at least two polar groups, of which one must be a primary, secondary or tertiary amino group, and the others can. be amino or hydroxyl groups or a mixture thereof. It may contain as many as six polar groups, those having two and three polar groups being most available and therefore being preferred. The latter amines are employed in the examples because of their low cost and availability. The amines, in addition to hydroxyl groups, can contain inert nonpolar substituents, such as halogen, which have been found not to reduce the activity of the compounds. Exemplifying compounds within the scope of the invention are diethylene triamine, tetraethylene pentamine, triethylene tetramine, dipropylene triamine, 2-amino-2-ethyl-1,3-propanediol, Z-amino- 2-methyl-l,3- propanediol, diethanol amine, aminoethyl ethanolamine, and polyglycol amines.

The amine need not be oil-soluble, but should be oildispersible. It should have a minimum boiling point of about 150 C. and should not decompose at least at temperatures up to 150 C. since its primary purpose is to stabilize the grease at high temperatures.

The amine is incorporated in the aerogel-base grease in an amount to impart high temperature stability. Ordinarily, a concentration of amine ranging from 0.25 to about 1% by weight of the aerogel-base grease gives satisfactory results. There is no reason to employ more amine than is necessary to produce the'desired. eifect, but excessive amounts do not harm, and amounts up to 5% or even higher have been successfully employed.

The amount of hydrophobic cationic surface-active agent to impart water-resistance to the aerogel grease in the form of 1-,8-hydroxyethyl-2-heptadecenyl imidazoline will vary from 0.1% to about 5%, depending upon the water stabilizing effect desired, the amount and nature of. the gelling agent used, and the economics involved.

In some instances, the composition containing the polyamine high temperature stabilizer may not display a long life when used continuously at high temperatures. A breakdown in high temperature stability at high temperatures if it appears is due to a decomposition, through oxidation, of the polyamine stabilizer of the invention. In such circumstances, it is desirable to include in the composition an antioxidant for the polyamine stabilizer. Conventional amine antioxidants which are more readily oxidized than the polyamines of the invention can be employed for this purpose. Tetramethyldiaminodiphenylmethane, available under the trade name Calco MB," is a particularly desirable antioxidant for the polyarnines of the invention. Only small quantities are required, and ordinarily an amount ranging from 0.1 to about 1% by weight of the aerogel base grease is ample. There is no reason to employ more antioxidant than is necessary to produce the desired efiect, but excessive amounts do no harm and amounts up to 5% can be used, if desired.

The composition is made simply by mixing the inorganic gelling agent, the oil, the amine, the cationic water stabilizer and the antioxidant in any order or manner.

In one embodiment, the amine, the cationic water stabilizer and, desirably, the antioxidant, can be incorporated with the inorganic gelling agent either by mixing directly or, if desired, by dissolving them in a volatile hydrocarbon solvent, such a pentane, adding oil, mixing the solution with the inorganic gelling agent and then evaporating the solvent.

Generally, the amine, the cationic water stabilizer and, optionally, the antioxidant are dispersed in the oil and the inorganic gelling agent added thereto and mixed therewith. Any simple mixing technique can be employed and, if desired, the mixture can be homogenized in a colloid mill, although this is not necessary.

The composition of the invention is not limited to the oil, gelling agent, the cationic water-stabilizer and amine. Any of the materials conventionally added to lubricants and greases can be included. The expression consisting essentially of as used herein is intended to refer to the components which are essential to the composition, namely, the oil, the inorganic gelling agent and the amine, and the expression does not exclude other components from the composition which do not render it unsuitable for lubrication, such materials being, for instance, the cationic water stabilizer, the antioxidant, high polymers to modify viscosity or viscosity index, materials to impart tackiness, lubricating solids such as graphite, antioxidant additives, corrosion inhibitors of various types, sulfur, additives to render the lubricant suitable for use in gears, for cutting, grinding, etc.

The following examples illustrate preferred embodiments of the invention. In the examples, water-resistant thickened lubricants are prepared to show the absence of an effect of the amine on the water resistance of the grease.

Examples 1 to 7 The base grease used in Examples 2 to 6 was a commercial water-resistant aerogel grease of the following formulation:

and commonly used in compounding greases.

A Frredel-Crafts reaction product, useful as a pour point depressant and sold by the Enjay Company, Inc.

Tetramethyldiaminodiphenylmethane.

This base grease is referred to hereafter as the aerogel W. R. base formula (Example 2). One of the amines listed in the following table, in the amount stated in the table, was incorporated in this grease by blending it with the oil, and then mixing in the other components of the grease (Examples 3 to 7). The resulting grease compositions were tested for high temperature stability by measurement of micropenetrations before and after heating to 400 F. The results obtained were compared with the results for the base grease formulation above, and also with non-water-resistant aerogel grease containing 10% Santocel C and No. 250 Solvent-Extracted neutral oil which did not contain Amine 0 (Example 1). This formula is referred to hereinafter as the aerogel base formula.

The grease is prepared for the determination of high temperature stability by placing approximately cc. of grease in a ml. beaker. The beakers are heated to the test temperatures by placing them in an aluminum block furnace. This furnace consisted of a solid block of aluminum heated by internal electrical heaters. Six holes, each large enough to accommodate a 150 cc. beaker, were drilled into the top of the block, together with a thermocouple, so that a measure of the temperature of the block could be obtained. In this manner, six beakers could be heated simultaneously. The beakers containing the grease were placed in the aluminum furnace and held there until the equilibrium temperature of the grease was 400 F. The samples were stirred at five-minute intervals during heating. After this the grease was allowed to cool to room temperature overnight and then was stirred vigorously with a spatula. Kaufman micropenetration measurements (industrial and Engineering Chemistry, Analytical Edition, volume 11, page 108, 1939) were obtained on the grease before and after the test procedure, and the results are expressed in the table below as percent increase in penetration.

TABLE II Kaufman micropenetrations Ex. Additive N 0. Percent Orig- After Percent added inal block increase l None (aerogel base formula). 122 243 100. 0 None (aerogel W. R. base 123 Soup formula). Diethylene triamine. 0.5 68 124 82. 2 d 1. 0 80 113 41. 2 0. 5 104 195 87. 5 Propylene diamine 0.5 92 152 65. 3 Ethylene diamine- 0.5 Soup The results show that an aerogel-base grease which does not contain Amine O in order to improve its water stability (Example 1) has a high temperature stability which, while superior to soap types, leaves much to be desired. When Amine O and other components are added to this base grease (Example 2) the stability at 400 F. is destroyed and the grease liquefies, and remains liquid after cooling. Through addition of the amines listed in amounts ranging from 0.5 to 1%, the eifectv of the Amine O is completely overcome and the aerogel grease possesses a better high temperature stability than the original aerogel base formula. Ethylene diamine (Example 7) is inefiective, showing the amine must have at least 3 carbon atoms.

Examples 8 to 12 Aerogel greases were prepared by blending an amine rnto the base oil and subsequently mixing this composition with Santocel and the other ingredients to prepare the. grease. These greases had theiollowing compo- Theresults show amines containing two amine groups sition: Q; I (Example 11) and one amine and onehydroxyl group (Example 12) to be effective with normal (250 SSU) and Example high 1000 SSLT) viscosity oils. It will be noted that the greases contalmng an amine and Santocel ARD "(Exam- 8 9 10 to 12 ples 11 and 12) had abetter high temperature stability than the corresponding grease (Example 10) which did Percent Percent Percent SanteeelO 10,0 10 not contain an amine. The high temperature stability 3&5: 11:: il "g5; of all of the greases containing an amine was good. ami e?" 1 .0 to 5 P Zfl JiV III I 012 01 0.' 5 Examples 13 to 19 it i base" 8'82 8'32 3'32 e ye solventfltmcte d new 81 on (250 or 1000 SSU An aerogel water reslstant grease of the following for at 100 F.) V85. 98 88.48 87. 98 mula was made up;

Amine 0.5 to 1% by weight of the above.

1 (l-B-hydroxyethyl-Zheptadeeenylimidazoline). 20 A B 2 An isobutylene polymer sold by the Enjay Company, Inc. and commonly used in compounding greases. Percent Percent 3 A Friedel-Orafts reaction product, useful as a pour point depressant Samuel ARD 8 0 8 0 and sold by the Enjay Company, Inc. mine 8 4 Tetramethyldiaminodiphenylmethane. 132mm, 0 o Paraflow 0.5 0.5 Oalco MB u 0. 5 0. 5 These greases were subjected to the block test and the 23 SSU at 210 micropenetrations of the greases measured by the Sohio method before and after heating at 400 F. lfi-hydroxyethyl-Z-heptadecenylimidazoline.

The Sohio micropenetration technique employed required a miniature cone and cup. The microcone employed was specially built, and its dimensions are comg A 18 called f" Aerogel water'reslstan'i base pared in T able .II with those of the standard ASTM cone, formula the table whlch f Fol-1211a B Is the ASTM Designation 217-48, described on page 143 of the wafer'rfz'slstant formal? i November 1948 edition of D-2 Specifications for Peamme m accordance f the fnvennon ,(and reducmg troleum Products. The cone and grease cup employed the bright Stock :accerdmgly) Order- Prepare an in obtaining the following test results required a miniaerogel gTe aSe Whlch is not only water'reslstanf ut also mum sample Size of 35 ml. 40 stable athigh temperatures. u a

In preparing these greases, the Amme"O and the TABLE I[[.MICROCONE DIMENSIONS amine to be tested were dissolved in a stock" solution of the base oil containing the other componentsi The ASTM Sohio Santocel was added to this solution and completely wett ed by stirring. The grease was prepared at-95- bymix- 0'11) Cone Cup ing for the time indicated in the following table, the Diametermm 65 78 20 43 bemg vaned so as to p m h a rea zlgeigtlllltgmm 45 17 tration of the aerogel water-resistant base formu1a..,If e mm Sur facmsq. 7,070 4,778 620 1, 470 this time 1s the same as or longer and/or if the original Volume, cc 290 35. 6 c n djgmjcup rmc 1 Q0135 penetratlon is the same as or less than that of the base fig g gfigj 3553-; 15f; "fig; formula, it is evident that the amine has either.- no or a Wt. oiassembly/sq. mm.eone surface- 0.021 0.021 beneficial effect on yield I O 810 mm d The penetration of the grease was taken before and after heating in the block described in Example 1 in ac- The following results were obtained on the aerogelcordancewith the Shell microcone pentration test (In-, base greases tested, containing the amines listed in the stitute Spokesman (NLGI), volume VI, Number 12, page amounts stated: 1, 1943).

TABLE IV Sohio microgenetrations, Base 051 Bloc test; PIX. Santoeel Additive (percent used) visgis- 1 l O (SSU) Original Final Percent increase 8 0 0.5 diethylene t'riamine 250 91 125 37 9 AR do 250 81 Z? 2:; 10 ARD" None 1,000 77 g3 g5 11 ARD. 0.5dietl1y1enetriamine 1,000 67 3g :4; 1Y2"... ARD 0.5 aminoethyl ethanola- 1,000 70 8., 3g

' mine. a

1 Same formula as Example 1.

1 0.5% additive.

A mixture of diethylene triamine, trietliylene tetramine, and tetraethylene pentamine.

The results show that incorporating the Amine O in the aerogel base formula appreciably increases the penetration and thus reduces the high temperature stability. The greases containing both Amine O and amines have good high temperature stability.

Examples to 27 A number of aerogel greases were prepared as follows: A fixed quantity of oil (78 SSU at 210 F. solventextracted bright stock) was weighed out into a 400 ml. beaker. 0.8% Amine O was added, and 1% of the amine additive was incorporated in the base oil. The oil mix was heated to 130 F. While being mixed with a Lightnin stirrer, and 8% Santocel ARD was mixed in with hand stirring. The resulting grease was allowed to stand overnight. An original penetration was then obtained using the Shell microcone penetration test and the grease was then subject to the block test. Grease samples exhibiting some degree of high temperature stability were cycled three or four times. Each sample was tested also for water stability and given a visual rating for consistency while at 400 F.

The additives tested included monoamines, hydroxyamines and diarnines. Data from these tests are given in the following table:

TABLE VI Block" test, Shell penetra- Ex. tions No. Additive 5O Orig. 1 2 3 4 Aerogel base formula 157 202 Aerogel W. R. base formula 139 200 226 Monoamines 20.... Armeen 10D (decylamine)-.- 179 21---- Armeen 12 (dodecylamine)- 140 22---. Anneen 14 (tetradecylamine)- 150 23---. Armeen 16 (cetylamine) 152 24---- Dodecyl dimethylamine 141 Diami'nea O 25--.. Diethylene triamiue 117 124 130 152 164 Hadron/amines 26.-.. 2-3imino-2-ethy1-1,3-propane- 167 192 199 203 27---- 2-amino-2-methyl 1,3 -pro- 112 158 168 192 panediol.

1 Same formula as Example 1.

In the examples, the high temperature stability of the aerogel greases is tested by heating the greases to 400 F. This is an extreme test, inasmuch as the highest temperature to which a grease is subjected under even extraordinary conditions of use is about 300 F., but it was adopted as a suitable test standard by which to measure the high temperature stability of the greases because a grease stable at 400 F. will definitely have the stability necessary to Withstand heating to 300 F. It will be understood that for normal purposes an aerogel grease need not be stable at temperatures above about 300 F, and that the greases of the invention at least meet this requirement. Where the term high temperature stability is used, it will be understood to mean that the aerogel grease is stable at at least 300 F.

The following hypothesis is given as a partial explanation of the reason to which is attributed the action of the amine in improving the high temperature resistance of aerogel grease, but the invention is not to be bound thereby.

Silica aerogels are known to be in the form of an extremely finely divided material and it is thought that it is capable of forming a colloidal structure in the oil vehicle employed in an aerogel grease. Mixing or stirring in formulating the grease serves to disperse the secondary aerogel agglomerates throughout the body of the oil. The aerogel occupies a greater volume than the liquid oil vehicle, and because of this it is probable that the colloidal structure is aided somewhat by a close packing of the solid silica gel particles, perhaps with mechanical interlocking. it is thought that the basis of the structure is a tying together of the various silica aerogel particles by hydrogen bonding between hydroxyl groups which remain attached to individual silicon atoms in the silica gel molecule.

In setting up the colloidal grease structure, it is postulated that the distances between adjacent hydroxyl groups on different particles of silica aerogel may be too great in some circumstances to form a binding, attractive force between particles. in this event, water, which is always present in the aerogel structure, serves to bridge the gap between adjacent particles through hydrogen bonding between the compound and the hydroxyl groups on the adjacent silica aerogel particles. Thus the water in effect aids in setting up the colloidal grease structure, and may also link it together, at least in part.

When the grease under static conditions is submitted to temperatures high enough to volatilize the water no apparent eifect is noticed at first, for there is no force to disarrange the structure. Consequently, penetration vs. temperature curves indicate that aerogel greases have excellent high temperature performance with a very low increase in consistency as the high temperature is increased. However, when this static state is disturbed by stirring, the structure can and does collapse, due to the absence of the water which has been volatilized and which formerly served as the connecting links between adjoining silica particles. in consequence, the structure passes from a gel state to a colloidal sol state. This explains why the transformation of the heated aerogel grease from a greaselike condition to a soupy condition occurs only after stirring and by stirring thus brings about an apparently irreversible gel-to-sol transformation. This transformation may be reversed to some extent by adding water to the soupy grease, tending to substantiate this hypothesis, but it is not possible to return the grease to its original condition.

Thus, on the basis of this hypothesis, incorporation in the grease, in accordance with the invention, of an amine having at least two polar groups which can form hydrogen bonds with hydroxyl groups and which is not volatile at the temperatures to which the grease may be subjected leads to a partial or complete displacement of water in the aerogel by amine, possibly before and in any event at the time water is volatilized at an elevated tem- 11 perature. The involatility of the amine prevents its loss during heating and thus prevents destruction of the col loidal grease structure when the aerogel grease is stirred after it has been heated to high temperatures. It'is also apparent from this that a hydrophobic amine which is immiscible with water could not function in this way because it could not act as a substitute for water in the hydrophilic gel structure.

We claim:

1. A water-resistant thickened lubricant of good temperature susceptibility properties, consisting essentially of a mineral lubricating oil of lubricating viscosity, an inorganic gelling agent imparting a greaselike consistency to the oil upon addition thereto, l-fl-hydroxyethyl-Z- heptadecenyl imidazoline, and a water-soluble amine having at least three carbon atoms and two polar groups and imparting high temperature stability.

2. A thickened lubricant of good temperature susceptibility properties in accordance with claim 1 wherein the amine is a hydroxyamine.

3. A thickened lubricant of good temperature susceptibility properties in'accordance with claim 1 wherein the amine is a polyamine.

ceptibility properties in accordance with claim 1 wherein the amine is diethylene triamine.

5. A thickened lubricant of good temperature susceptibility properties in accordance with claim 1 wherein the amine is aminoethylethanolamine.

6. A thickened lubricant of good temperature susceptibility properties in accordance with claim 1 wherein the amine is propylene diamine.

7. A thickened lubricant of good temperature suscep tibility properties in accordance with claim 1 wherein the amine is tetraethylene pentamine.

8. A thickened lubricant of good temperature susceptibility properties in accordance with claim 1 wherein th amine is aminomethylpropanediol.

References Cited in the file of this patent UNITED STATES PATENTS 2,554,222 Stross May 22, 1951 2,563,606 Kimberlin et a1 Aug. 7, 1951 2,573,650 Peterson Oct. 30, 1951 2,711,393 Hughes et al. June 21,1955 

1. A WATER-RESISTANT THICKENED LUBRICANT OF GOOD TEMPERATURE SUSCEPTIBILITY PROPERTIES, CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL OF LUBRICATING VISCOSITY, AN INORGANIC GELLING AGENT IMPARTING A GREASELIKE CONSISTENCY TO THE OIL UPON ADDTION THERETO, 1-B-HYDROXYETHYL-2HYEPTADECENYL IMIDAZOLINE, AND A WATER-SOLUBLE AMINE HAVING AT LEAST THREE CARBON ATOMS AND TWO POLAR GROUPS AND IMPARTING HIGH TEMPERATURE STABILITY. 